How to Warm Up an IP Address: How Much and When?

Lately, we’ve been talking a lot about the importance of warming up an IP address. Now that you know that warming up an IP involves ramping up email volume over a specified period of time, how much should you be sending and when?

Email Volume and Timeline

For IP warm up, the volume of email and over what period of time is different for all senders. How many emails you send depends on your own total email volume, but in any case you must send enough email at enough frequency so that your email reputation can be tracked.

As a general baseline, you should send at least 50,000 emails per month at least twice per month (for 100,000 emails total) in order to need to warm up your IP. (This means that if your email volume is going to be really small but steady on a dedicated IP, you don’t need to worry about warming up—you’re off the hook!) Most reputation systems only store data for 30 days, so you should not go 30 days or more without sending on an IP. If you do, then you will need to warm it up again.

Where To Start

The biggest hurdle is knowing where to start.

1) First, choose a segment of your email file to warm up. For instance, choose your welcome message as your trial segment for your new IP. Welcome messages do several good things; they serve as a permission reminder, they reiterate your value proposition, and they have calls to action to generate response. The point is to select a mail stream that has strong permission practices. This will help build your reputation and solidify your legitimacy as a sender in the eyes of the ISPs.

2) Once you’ve decided on a segment, determine the amount of email you should send. Once you determine your volume, send that same number of emails for several days in a row and then gradually increase your volume. This process can last up to 60 days. However, the majority of SendGrid clients warm up their IPs within 30 days with some completing the process in as little as 1-2 weeks. To determine speed, use your results as a guide. If you are attaining good email deliverability with high engagement rates, then you can try to speed up the process. However, if you get throttled, tap the brakes and slow it down.

Below are a few suggested schedules for ramping up your sending.

Sample IP Warm Up Schedules

(Please note: These sample schedules are intended to be a suggestion only. Every sender is different and you will need email deliverability experts to help you determine the right warm up volume and frequency for your email program.)

Email Marketing Campaigns

Conservative Approach:

Estimate your total monthly email volume and divide that number by 30. Then, try to spread your sending evenly over the first 30 days, based on that calculation. For example: if you will send 90,000 emails/month, you should start off sending 3,000 per day over the first month.

Aggressive Approach:

Instead of dividing total monthly volume by 30, divide it by 15. For example: say you still need to send the same 90,000 email/month, but you need the emails to reach your recipients in half as long of a time frame, send 6,000 per day for the first 15 days.

Transactional Email

Established businesses:

If you are already sending a ton of email, and you decide to move to an ESP for the first time or switch to a new vendor, you should migrate your sending a little bit at a time. One way to do this is to split your traffic and move small portions of it to the new IP over time. Alternatively, if you are already maintaining multiple mail servers, you can move your servers over to your new IP one at a time.

New businesses:

Typically, the organic growth of your business will, by its nature, create an ideal ramp. Since transactional email is usually dependent on the number of users you have, the growth in your customer base will create a nice, comfortable growth curve in your email volume.

Maintain warm up across ALL ISPS

Now that you’ve seen some sample schedules, it’s important to remember that you must maintain a steady volume during the entire warm up period at EACH ISP. (i.e. Split up your warm up schedule so each ISP is receiving a comparable amount of mail each day—don’t warm up Gmail on Monday, Yahoo! on Tuesday, etc.—evenly disperse your mail to each ISP on each day of warm up.) If not, your sending activity looks sporadic and you won’t be able to build a solid reputation.

What’s Next?

Now that you have an idea of when to warm up your IP and with how much mail, you should think about how to maintain the good reputation that you’re earning with the ISPs by implementing these strong IP warm up practices. For more information on how to do so, download our free guide: How To Warm Up an IP.

Author: Carly Brantz

Carly Brantz is a veteran in the email deliverability space working to make email simple and easy for developers by regularly writing whitepapers, research briefs and blog posts about email, technology and industry trends.